P&S Data Quality

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NOTE: This does not yet incorporate a second discussion in April.  
 There will be a six hour workshop at the 2006 Summer Meeting 
 (see discussion May 23).

Contents

Objective

Create a common set of data quality metrics across all Federation data products. Data providers can provide measures for their own products. 3rd parties can provide their own ratings. Quality can refer to accuracy, completeness, and consistency. It is not clear how to measure consistency. It is desirable to provide quality assurance.

We would like to create a 1-10 Data quality scale, where:

 1 = no accuracy claimed
10 = fully reliable data that has withstood the test of time

This measure can be applied to any of the quality dimensions:

Quality Dimensions

  1. Sensor/Instrument (well calibrated, stable, checked across instruments, V/V)
  2. Spacecraft (locational and communication accuracy)
  3. Environment Issues (contamination from clouds, rainfall, ground, sea, dirt, etc.)
  4. Data Processing (accuracy of interpolation, algorithms, ancillary source data)

Our Task

Create a 1-10 scale for each dimension. We will work with Federation members to associate a quality description with each value.


Other topics

Quality assurance (someone tags it as valid)
Useful metadata provided?
Instrument Verification and Validation
Data processing
Re-processing tag and notification
input errors and forcings
re-gridding
missing data
Usage issues
High enough resolution?
Valid inference about what is measured
Chain of Custody (for legal use)

Completeness Can we come up with categories of data completeness?

3rd party ratings

NCDC
NCDC Certified data (only states that it is in the archive -- designates as official, not a quality statement)
Dataset docs use FGDC quality section, with different levels of detail
GCMD
DIF records have some minimum required fields to accept
then have a text field to describe quality
ECHO
"measured parameters" from ECS model
QA percent cloud cover; missing pixels;
CLASS/Climate Data Record
Maturity Model approach for data (John Bates application from software maturity)
Level of maturity (five levels of improved treatment)
See CDR Maturity paper
FGDC
Whole section on quality, text only
Testimonials
Peer review

Discussion

Completeness

  • Is this a measure of quality?
Depends on stated offering from the provider; if they claim it is complete and it isn't

Assertions about datasets

We may want some standard for claiming and measuring how valid a claim may be


Additional Questions

  • What common data quality standards can the Federation offer within the Earth Information Exchange?
  • How can we enforce these standards within the Earth Information Exchange?
  • Are there similar ratings for "data services"?
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